Phthalocyanine compounds are useful as paints, printing inks, catalysts, and electronic materials. In recent years, they have been extensively studied particularly for their use as electrophotographic photoreceptor materials, optical recording materials and photoelectric conversion materials.
Electrophotographic photoreceptors using a hydroxymetal phthalocyanine pigment, such as dihydroxygermanium phthalocyanine, dihydroxytin phthalocyanine or dihydroxysilicon phthalocyanine, are disclosed, e.g., in U.S. Pat. No. 4,557,989.
Application of an organometallic compound having a hydrolyzable functional group or a hydrolysis product thereof to an electrophotographic photoreceptor using a phthalocyanine compound is reported in JP-A-55-127565 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-59-19946, and JP-A-60-130745. Application of a titanium coupling agent to hydroxytitanyl phthalocyanine is mentioned in Japan Hard Copy '92, pgs. 153-156 (1992) while the report says that the application has no effect on electrophotographic properties of the phthalocyanine compound. Any of these reports makes no mention of application of an organometallic compound having a hydrolyzable functional group or a hydrolysis product thereof to a hydroxymetal or hydroxysilicon phthalocyanine pigment.
Where a hydroxymetal or hydroxysilicon phthalocyanine is dispersed in a binder resin in a usual manner for the production of an electrophotographic photoreceptor, it has poor dispersibility only to provide a pigment dispersion having insufficient coating properties and insufficient preservability for forming a smooth coating film. The resulting photoreceptor fails to exhibit satisfactory reproducibility of electric characteristics and tends to cause image defects, such as fog and black spots.